Clinical predictors of morbidity and mortality in patients with myocardial infarction or revascularization who underwent cardiac rehabilitation, and importance of diabetes mellitus and exercise capacity

Abstract

This investigation was a prospective, follow-up study to assess whether baseline clinical and investigational parameters were predictors of cardiovascular morbidity and mortality in patients enrolled into the cardiac rehabilitation program. A cohort of 418 patients (70% were men) with coronary heart disease was followed up 3.2 +/- 1.1 years. Two hundred twenty-seven of them (54%) had a recent myocardial infarction (MI), with a thrombolytic rate of 54%. Percutaneous transluminal coronary angioplasty (PTCA) was performed in 45% of patients. The covariates assessed include age, gender, smoking habit, body mass index, the presence of hypertension or diabetes mellitus, exercise habit, site and severity of MI, status of thrombolytic therapy, peak creatine phosphokinase, plasma lipid profiles, ejection fraction, PTCA performed, number of diseased coronary arteries, and exercise capacity. Low-density lipoprotein cholesterol decreased significantly (3.2 +/- 1.0 vs 2.7 +/- 0.7 mmol/L, p < 0.001). The cumulative mortality was 13%. In a univariate model, the parameters that significantly predict mortality included older age, diabetes, low exercise capacity (< or = 4 metabolic equivalents) 3-vessel disease, those without PTCA performed, and a low ejection fraction. In the Cox proportional-hazards model analysis, the independent factors were coexisting diabetes (chi-square 6.1, p = 0.01) and a low metabolic equivalent (chi-square 6.5, p = 0.01). One hundred six patients were rehospitalized for nonfatal cardiovascular events that included unstable angina (48%), heart failure (21%), acute MI (6%), symptomatic arrhythmia (6%), and severe hypertension (1%). Factors that independently predicted rehospitalization were low exercise capacity (p = 0.02) and the presence of diabetes (chi-square 4.8, p = 0.03). Diabetes was also associated with more episodes of hospital admission (2.3 +/- 2.1 vs 1.6 +/- 1.4, p = 0.04) and a longer cumulative hospital stay (25.5 +/- 34.6 vs 11.4 +/- 19.6 days, p = 0.02). Thus, in patients with MI or after PTCA receiving conventional medical therapy, the cardiac rehabilitation program should focus on aggressive diabetic control and enhancement of exercise capacity.